# Inductors. AC Theory. Module 3

Size: px
Start display at page:

## Transcription

1 Module 3 AC Theory What you ll learn in Module 3. Section 3.1 Electromagnetic Induction. Magnetic Fields around Conductors. The Solenoid. Section 3.2 Inductance & Back e.m.f. The Unit of Inductance. Factors affecting Inductance. Voltage and e.m.f. Back e.m.f. Self Induction. Section 3.3 Practical. Introduction are components that are simple in their construction, consisting of coils of insulated copper wire wound around a former that will have some type of core at its centre. This core might be a metal such as iron that can be easily magnetised; or in high frequency inductors, it will more likely to be just air. depend for their action on the magnetic field that is present around any conductor when it is carrying a current. If the wire coil is wound around a core made of a material that is easily magnetised, such as iron, then the magnetic field around the coil is concentrated within the core; this greatly increases the efficiency of the inductor. The Solenoid. Practical. Inductor schematic symbols. Section 3.4 Inductor Colour Codes. Colour codes for. Section 3.5 Quiz. AC THEORY MODULE 03.PDF 1 E. COATES

2 in AC Circuits. are extensively used in alternating current (AC) applications such as radio, TV and communications equipment, and in these systems, how inductors react to AC signals of different frequencies is very useful Chokes. Another name used for an inductor is a "Choke"., being just coils of copper wire, will allow DC to pass easily, but when AC is applied, inductors create an opposition to current flow that increases, as the frequency of the alternating current increases. Therefore AC is prevented from flowing or is "Choked off" while DC is allowed to pass. This effect is used in power supply circuits where the public AC mains (line) supply has to be converted to a DC supply suitable for powering electronic circuits. Energy Storage. The magnetic field around an inductor is a store of energy (from the current that caused the field). When the current is turned off, the energy stored in the magnetic field is returned to the inductor, causing a current to flow in the opposite direction. This can produce a pulse of high voltage across the coil. The pulse of energy can be a problem in some electronic circuits and can easily destroy other components if not properly controlled, but it can also be extremely useful; such high voltage pulses produced by an inductor are used to create the spark that ignites the petrol in automobile engines. of many types. The physical size of inductors varies greatly, depending on the power being handled, and on the frequency of the AC being used; from huge power transformers in power stations and the electricity supply grid, to tiny inductors in radio equipment consisting of a few turns of wire and only a few millimetres across. AC THEORY MODULE 03.PDF 2 E. COATES

3 Module 3.1 Electromagnetic Induction. Magnetic Field Around a Conductor. A conductor carrying an electric current will produce a magnetic field around the conductor as shown in Fig This field has a circular shape and exists along the whole length of the conductor. Because of its circular shape, the magnetic field does not have specific north or south poles, but is considered to flow in a continuous circular loop towards an undefined north pole. Fig Magnetic Field Around a Conductor. Right Hand Grip Rule. The direction of a magnetic field around a conductor can be remembered using the right hand grip rule shown in Fig Imagine grasping a conductor in the right hand as shown, with the thumb indicating the direction of conventional current flow from positive to negative. The fingers of the right hand, curled around the conductor indicate the direction of flow of magnetic flux. Fig Right Hand Grip Rule. Magnetic Fields Around Parallel Conductors. If two parallel conductors carry the same current, the direction of the magnetic fields around each conductor will interlink and oppose each other between the conductors as shown in Fig forming an area of zero magnetic flux (no flow) between the conductors, this happens between adjacent conductors around the axis of a coil. Fig Magnetic Field Around Parallel Conductors Magnetic Fields Around Coils. When the conductor is bent into a loop or coil however, the direction of the magnetic fields inside the coil coincide, concentrating the magnetic flux within the coil as shown in Fig Fig Magnetic Field Around Looped Conductors. AC THEORY MODULE 03.PDF 3 E. COATES

4 The Solenoid. When wire coils are formed into a series of continuous loops called a solenoid, the effects described above produce a magnetic field pattern that is similar to that around a bar magnet, as shown in Fig Increasing or decreasing the current through the inductor increases or decreases the strength of the magnetic field, giving the effect of a bar magnet, but with a variable field strength. This changing magnetic field can have several effects. It can be used to produce movement, for example in electric motors, or it can be used produce electrical effects in other conductors affected by the field. Fig Magnetic Field Around a Solenoid and a Bar Magnet. As this module deals with AC signals in static components such as inductors and transformers, (rather than moving machines such as motors or generators) the effects described relate changes in the magnetic fields around static inductors, to changes in current through the those inductors. Terms used in electromagnetism. Magnetic Flux is the name given to the magnetic equivalent of electric current. It is the flow of magnetism from the north to the south pole of a magnet. Magnetic Flux flows along lines of magnetic force that make up a magnetic field. Just like electric current, it is easier for magnetic flux to flow through some materials than others, soft iron for example has a very high permeability. That means, it is very easy for magnetic flux to flow through it. High permeability can also be described as a very low reluctance to the flow of magnetic flux (the magnetic equivalent of resistance). Air has more reluctance and so is less permeable than iron. It is therefore easier for a flux to flow through iron than through air, and many electromagnetic devices use materials such as iron to concentrate magnetic flux into a small area and so increase the effectiveness of devices such as transformers, motors and electromagnets. AC THEORY MODULE 03.PDF 4 E. COATES

5 Module 3.2 Inductance A current generated in a conductor by a changing magnetic field is proportional to the rate of change of the magnetic field. This effect is called INDUCTANCE and is given the symbol L. It is measured in units called the henry (H) named after the American Physicist Joseph Henry ( ). One henry is the amount of inductance required to produce an e.m.f. of 1 volt in a conductor when the current in the conductor changes at the rate of 1 Ampere per second. The Henry is a rather large unit for use in electronics, with the milli-henry (mh) and microhenry (μh) being more common. These units describe one thousandth and one millionth of a henry respectively. Although the henry is given the symbol (capital) H, the name henry, applied to the unit of inductance uses a lower case h. The plural form of the henry may be henries or henrys; the American National Institute of Standards and Technology recommends that in US publications henries is used. Factors Affecting Inductance. The amount of inductance in an inductor is dependant on: a. The number of turns of wire in the inductor. b. The material of the core. c. The shape and size of the core. d. The shape, size and arrangement of the wire making up the coils. Because inductance (in henries) depends on so many variable quantities, it is quite difficult to calculate accurately; numerous formulae have been developed to take different design features into account. Also these formulae often need to use special constants and tables of conversion data to work with the required degree of accuracy. The use of computer programs and computer-aided design has eased the situation somewhat. However, external effects caused by other components and wiring near the inductor, can also affect its value of inductance once it is assembled in a circuit, so when an accurate value of inductance is required, one approach is to calculate an approximate value, and design the inductor so that it is adjustable. Fig Variable Inductor. A typical formula for approximating the inductance value of an inductor is given below. This particular version is designed to calculate the inductance of "A solenoid wound with a single layer of turns of infinitely thin tape rather than wire, and with the turns evenly and closely spaced." Where: L is the inductance in henries. d is the diameter of the coil in metres. n is the number of turns in the coil. l is the length of the coil in metres. For coils not conforming exactly to the above specification extra factors must be incorporated. Voltage and e.m.f. A voltage induced into a conductor is called an e.m.f. (electro motive force) because its source is the changing magnetic field around and external to the conductor. Any externally produced voltage AC THEORY MODULE 03.PDF 5 E. COATES

6 (including those produced by an external battery or power supply) is called an e.m.f., whilst a voltage (a potential difference or p.d.) across an internal component in a circuit is called a voltage. Back e.m.f. A back e.m.f.(also called a Counter e.m.f.) is an e.m.f. created across an inductor by the changing magnetic flux around the conductor, produced by a change in current in the inductor. Its value can be calculated using the formula: Where: E is the induced back e.m.f. in volts L is the inductance of the coil in henries. ΔI is the change in current, in amperes. Δt is the time taken for the change in current, in seconds. Notes: Δ (Greek D Delta) denotes a difference or change in a property. So the formula describes the back e.m.f. as depending on the inductance (in henries) multiplied by the rate of change in current (in amperes per second). The minus sign before L indicates that the polarity of the induced back e.m.f. will be reversed compared with the changing voltage across the conductor that originally caused the changing current and consequent changing magnetic field. Remember that when working in practical values of milli or micro henries that all values used in the formula must be converted to the standard values of henries amperes and seconds as described in our Maths Tips booklet. Example Because the value of back e.m.f. depends on the rate of change of the current, it will be greatest when the fastest change occurs. For example, the rate of change is extremely fast whenever the current through an inductor is switched off; then the change can be from maximum to zero in just a few milliseconds. Imagine that an inductor of 200mH connected across a supply of 9V is passing a current of 2amperes. When the current is switched off, it collapses to zero in 10ms, what would be the back e.m.f. generated across the coil? E = 200mH x 2A / 10ms or E =200 x 10-3 x 2/10 x 10-3 = 40volts So the back e.m.f. generated at switch off is more than 4 times higher than the supply voltage! AC THEORY MODULE 03.PDF 6 E. COATES

7 These high voltage pulses that occur when an inductive component such as a motor or relay coil is switched off, can potentially cause damage to the output transistor or integrated circuit switching the device. Therefore essential protection is provided by including a diode in the output stage as shown in Figs and Back e.m.f. Protection The protection diode in Fig connected across the inductor is normally reverse biased, as the voltage on its cathode, connected to the +V supply rail, will be more positive than its anode on the collector of the transistor. At switch off however, a large voltage spike of opposite polarity appears across the inductor, due to the collapsing magnetic field. For the duration of this voltage spike, the collector of the transistor could be at a higher potential than the supply, except that if this happens, the diode will become forward biased and prevent the collector voltage rising any higher than the supply rail. Fig shows a popular I.C. (ULN2803) for switching inductive loads. The outputs of the eight inverting amplifiers are each protected by a diode, having their common cathodes connected to the positive supply rail +V on pin 10. Self-induction Fig Back e.m.f. Protection Fig Protection Diodes in the The effect of an inductor inducing an e.m.f. into itself is called Self Induction (but often referred to simply as Induction). When an inductor induces an e.m.f. into a separate nearby inductor, this is called Mutual Induction and is a property used by transformers. The way self-induction works depends on two interlinked actions occurring simultaneously, and on each of these actions depending on the other. Action 1. Any conductor, in which the current is changing, will produce a changing magnetic field around it. Action 2. Any conductor within a CHANGING magnetic field will have a changing e.m.f. induced into it. The value of this induced e.m.f. and the amount of induced current it produces in the conductor will depend on the rate of change of the magnetic field; the faster the flux of the field changes, the greater will be the induced e.m.f. and its consequent current. AC THEORY MODULE 03.PDF 7 E. COATES

8 The changing magnetic field created around a conductor by the changing current in the conductor causes a varying e.m.f. to be set up across that conductor. This varying e.m.f. in turn produces a varying current flowing in the opposite direction to the original current. The changes in this current therefore oppose the changes in the original current. The effect of Action 2 is therefore to limit the changes occurring because of Action 1. If the original current is increasing, the induced current will slow the rate of increase. Similarly, if the original current is decreasing, the induced current will slow the rate of decrease. The overall result of this is to decrease the amplitude of the AC current through the inductor and so also reduce the amplitude of the AC voltage across the inductor. Because the strength of the magnetic field set up by the original current is dependent on the rate (speed) of change of current, an inductor reduces the flow of alternating current (AC) more at high frequencies than at low. This limiting effect produced by the induced e.m.f. will be greater at higher frequencies because at high frequencies, the current and therefore the flux is changing more rapidly. The name given to this effect is Inductive Reactance. Inductive Reactance. Reactance produces an opposition to the flow of alternating current. Like resistance, it is measured in Ohms, but because resistance has the same value at any frequency and the opposition to AC found in inductors varies with frequency, it cannot be called resistance. Instead, it is called Reactance (X). Capacitors also have the property of reactance but they respond to frequency in a different way, therefore there are two types of reactance; inductors have Inductive Reactance (X L ), and capacitors have Capacitive Reactance (X C ). AC THEORY MODULE 03.PDF 8 E. COATES

9 Module 3.3 Practical The Right Hand Curl Rule for a Solenoid. Many practical inductors are based on the solenoid. Because of its shape, the lines of magnetic flux are concentrated along the centre line of the coil and this produces a magnetic field with a north and a south pole. To find out which end of the solenoid is the north pole, imagine grasping the solenoid in the right hand as shown in Fig with the fingers curled around the solenoid in the direction of CONVENTIONAL CURRENT FLOW, from positive to negative around the solenoid, the right thumb is laid along the side of the solenoid and will be pointing towards the solenoid s north pole. Fig Practical. Fig The Right Hand Curl Rule. a b c d e f AC THEORY MODULE 03.PDF 9 E. COATES

10 (a) Air Cored Simple air cored inductors are used in many circuits operating in the 1MHz to several hundred MHz range, including radio and TV receivers. (b) AM Radio Antennas AM radio receivers use internal antennas that have a number of inductors wound around a ferrite rod. These are combined with fixed and variable capacitors to enable the radio to be tuned to the various station frequencies. (c) Colour Coded Axial Lead-out Looking very similar to resistors, colour coded inductors have typical values from 0.1µH to 1mH. The value given by the colour bands are given by a standard EIA 4 band code for commercial inductors, and by a Military Standard 5 band code for military types On which the first band is always silver (denoting a military component) and the fifth band has an extended range of tolerances to indicate close tolerance types of +/- 1% to 4% (d) Toroidal Toroidal (ring shaped) cores are very efficient at concentrating the magnetic flux within the coil and are often used for large current inductors and transformers, such as those used in power supplies. (e) SMD Chip Surface mounted multi-layer chip inductors are tiny; often only 3 or 4mm across. Although this physical size limits the values of inductance that can be achieved, typical values of less than 1µH up to a few hundred µh are useful for many radio frequency and communications applications. The example shown is part of a hard disk drive control circuit. (f) at UHF Air cored inductors for UHF applications may consist of only one or two turns of wire. In some cases even a straight-line conductor, a few millimetres long can have enough inductance to form a useful inductor or transformer. In these situations the exact positioning of inductors relative to other components or metal casing, such as screening cans, is vitally important. During construction individual inductances may have had their inductance fine-tuned by slightly altering their positions, or the spacing between turns. Fig Inductor (Schematic) Circuit Symbols. AC THEORY MODULE 03.PDF 10 E. COATES

11 Module 3.4 Inductor Colour Codes Fig Four Band Standard E I A Colour Code For. Band Meaning 1 st Digit 2 nd Digit (No. of zeros) Tolerance % Gold.0 (divide by 10) +/-5% Silver.00 (divide by 100) +/-10% Black 0 0 No Zeros +/-20% Brown Red Orange 3 3,000 Yellow 4 4 0,000 Green 5 5 Blue 6 6 Violet 7 7 Grey 8 8 White 9 9 AC THEORY MODULE 03.PDF 11 E. COATES

12 Fig Five Band Military Standard Inductor Colour Code Band Meaning (See Notes) Mil. Spec. Digit or Dec. point Digit or Dec. point Digit (or Multiplier) Tolerance % Gold Decimal point Decimal point +/-5% Silver Always Silver double width +/-10% Black 0 0 Brown 1 1 Red 2 2 Orange 3 3 Yellow (or x 1) 1 (or x 10) 2 (or x 100) 3 (or x 1,000) 4 (or x 10,000) +/-20% +/-1% +/-2% +/-3% +/-4% Green Blue Violet Grey White See notes on next page: AC THEORY MODULE 03.PDF 12 E. COATES

13 Notes: The military standard for cylindrical inductors specifies 5 coloured bands The same colours are used as in the EIA 4 band code, but: For band 1, a double width sliver band is used to signify Military Standard. For values less than 10µH: Bands 2, 3 and 4 indicate the value of inductance in µh A gold band might be used in either band 2 or band 3. In either of these two bands, gold indicates a decimal point and band 4 is used as a digit instead of a multiplier band. When no gold band is present in bands 2 or 3, band 4 is a multiplier band. For example: For example: If bands 2,3 and 4 were red, gold, red the value would be 2.2 µh If bands 2,3 and 4 were gold, yellow, violet the value would be 0.47 µh (470nH) Band 5 indicates the tolerance between 1% and 20% For values of 10µH or more: Bands 2 and 3 represent basic value, and band 4 gives the number of zeros. If bands 2, 3 and 4 were red, violet, orange the value would be µh Chip (SMD) For inductors of a very small physical size, coloured dots may be used instead of bands. In such cases, The silver dot indicating a Military (Mil) specification will be larger than the other dots and will be placed a the beginning of the dot sequence. In some cases only a single coloured dot is used, and for their meaning it is necessary to refer to individual manufacturers data for accurate interpretation. Dot code examples from Coilcraft Inc. Dot code examples from Viking Tech Corporation. AC THEORY MODULE 03.PDF 13 E. COATES

14 Module 3.5 Quiz Try our quiz, based on the information you can find in Module 2. Check your answers on line at What you should know. After studying Module 3, you should: Be able to describe electromagnetic effects in static conductors. Be able to describe inductors, units of inductance and circuit symbols. Be able to describe Self Induction and the effects of Back (counter) e.m.f.. Be able to describe frequency effects in inductors. Be able to describe constructional features and typical applications of inductors. 1. What type of is inductor illustrated in Fig 3.5.1? a) A laminated iron cored inductor. b) A ferrite cored inductor. c) A preset inductor. 2. d) An air cored inductor. The inductance of an inductor will be affected by which property or properties of the inductor's core? a) The material of the core. b) The material and size of the core. c) The shape and size of the core. 3. d) The shape, size and material of the core. Which of the following ranges of inductance values would be most commonly encountered in electronic circuits? a) henrys. b) milli-henrys. c) henrys and milli-henrys. 4. d) milli-henrys and micro-henrys. Which of the following properties of an inductor change with the applied frequency: a) Reactance b) Inductance c) Reluctance d) Resistance AC THEORY MODULE 03.PDF 14 E. COATES

15 5. What is the value of the inductor shown in Fig 3.5.2? a) 27µH +/-10% b) 2.7µH +/-20% c) 270µH +/-10% 6. d) 27µH +/-5% Which of the following describes what happens to a non-moving conductor within a changing magnetic field? a) The conductor will have a changing e.m.f. induced into it. b) An e.m.f. will be induced into the conductor, proportional to conductor s reactance. c) The conductor will have a steady current induced into it. 7. d) A current will be induced into the conductor, inversely proportional to conductor s reluctance. Which of the formulae shown in Fig would be used for calculating back e.m.f.? a) b) c) d) 8. Complete the following statement: The magnetic field produced by a solenoid shaped inductor is: a) Concentrated within, and along the axis of the coil. b) Less likely to produce a back e.m.f. effect than in other coil shapes. c) Most effective at very low frequencies. d) More likely to produce a back e.m.f. effect than in other coil shapes. 9. When using the right hand curl rule for a solenoid, what do the fingers of the right hand indicate? a) The direction of conventional current flow. b) The direction of the solenoid s north pole. c) The direction of the solenoid s south pole. d) The negative terminal of the solenoid. 10. What would be the value of back e.m.f. induced at switch off, in a 3.3mH inductor passing a current of 250mA, assuming the time for the current to decay to zero was 50µs? a) 10V b) 16.5V c) 22V d) 32.7V AC THEORY MODULE 03.PDF 15 E. COATES

### DIRECT CURRENT GENERATORS

DIRECT CURRENT GENERATORS Revision 12:50 14 Nov 05 INTRODUCTION A generator is a machine that converts mechanical energy into electrical energy by using the principle of magnetic induction. This principle

### Power Supplies. 1.0 Power Supply Basics. www.learnabout-electronics.org. Module

Module 1 www.learnabout-electronics.org Power Supplies 1.0 Power Supply Basics What you ll learn in Module 1 Section 1.0 Power Supply Basics. Basic functions of a power supply. Safety aspects of working

### Line Reactors and AC Drives

Line Reactors and AC Drives Rockwell Automation Mequon Wisconsin Quite often, line and load reactors are installed on AC drives without a solid understanding of why or what the positive and negative consequences

### Diodes have an arrow showing the direction of the flow.

The Big Idea Modern circuitry depends on much more than just resistors and capacitors. The circuits in your computer, cell phone, Ipod depend on circuit elements called diodes, inductors, transistors,

### April 1. Physics 272. Spring 2014 http://www.phys.hawaii.edu/~philipvd/pvd_14_spring_272_uhm.html. Prof. Philip von Doetinchem philipvd@hawaii.

Physics 272 April 1 Spring 2014 http://www.phys.hawaii.edu/~philipvd/pvd_14_spring_272_uhm.html Prof. Philip von Doetinchem philipvd@hawaii.edu Phys272 - Spring 14 - von Doetinchem - 164 Summary Gauss's

### Inductors & Inductance. Electronic Components

Electronic Components Induction In 1824, Oersted discovered that current passing though a coil created a magnetic field capable of shifting a compass needle. Seven years later, Faraday and Henry discovered

### Objectives. Capacitors 262 CHAPTER 5 ENERGY

Objectives Describe a capacitor. Explain how a capacitor stores energy. Define capacitance. Calculate the electrical energy stored in a capacitor. Describe an inductor. Explain how an inductor stores energy.

### Eðlisfræði 2, vor 2007

[ Assignment View ] [ Print ] Eðlisfræði 2, vor 2007 30. Inductance Assignment is due at 2:00am on Wednesday, March 14, 2007 Credit for problems submitted late will decrease to 0% after the deadline has

### Oscillators. 2.0 RF Sine Wave Oscillators. www.learnabout-electronics.org. Module. RF Oscillators

Module 2 www.learnabout-electronics.org Oscillators 2.0 RF Sine Wave Oscillators What you ll Learn in Module 2 Section 2.0 High Frequency Sine Wave Oscillators. Frequency Control in RF Oscillators. LC

### Induced voltages and Inductance Faraday s Law

Induced voltages and Inductance Faraday s Law concept #1, 4, 5, 8, 13 Problem # 1, 3, 4, 5, 6, 9, 10, 13, 15, 24, 23, 25, 31, 32a, 34, 37, 41, 43, 51, 61 Last chapter we saw that a current produces a magnetic

### Chapter 22: Electric motors and electromagnetic induction

Chapter 22: Electric motors and electromagnetic induction The motor effect movement from electricity When a current is passed through a wire placed in a magnetic field a force is produced which acts on

### Slide 1 / 26. Inductance. 2011 by Bryan Pflueger

Slide 1 / 26 Inductance 2011 by Bryan Pflueger Slide 2 / 26 Mutual Inductance If two coils of wire are placed near each other and have a current passing through them, they will each induce an emf on one

### W03 Analysis of DC Circuits. Yrd. Doç. Dr. Aytaç Gören

W03 Analysis of DC Circuits Yrd. Doç. Dr. Aytaç Gören ELK 2018 - Contents W01 Basic Concepts in Electronics W02 AC to DC Conversion W03 Analysis of DC Circuits (self and condenser) W04 Transistors and

### Edmund Li. Where is defined as the mutual inductance between and and has the SI units of Henries (H).

INDUCTANCE MUTUAL INDUCTANCE If we consider two neighbouring closed loops and with bounding surfaces respectively then a current through will create a magnetic field which will link with as the flux passes

### Electronics and Soldering Notes

Electronics and Soldering Notes The Tools You ll Need While there are literally one hundred tools for soldering, testing, and fixing electronic circuits, you only need a few to make robot. These tools

### PHYS 222 Spring 2012 Final Exam. Closed books, notes, etc. No electronic device except a calculator.

PHYS 222 Spring 2012 Final Exam Closed books, notes, etc. No electronic device except a calculator. NAME: (all questions with equal weight) 1. If the distance between two point charges is tripled, the

### DC GENERATOR THEORY. LIST the three conditions necessary to induce a voltage into a conductor.

DC Generators DC generators are widely used to produce a DC voltage. The amount of voltage produced depends on a variety of factors. EO 1.5 LIST the three conditions necessary to induce a voltage into

### Aircraft Electrical System

Chapter 9 Aircraft Electrical System Introduction The satisfactory performance of any modern aircraft depends to a very great degree on the continuing reliability of electrical systems and subsystems.

### GENERAL POWER SYSTEM WIRING PRACTICES APPLIED TO TECNADYNE DC BRUSHLESS MOTORS

1/5/2006 Page 1 of 6 GENERAL POWER SYSTEM WIRING PRACTICES APPLIED TO TECNADYNE DC BRUSHLESS MOTORS 1. Introduction The purpose of this application note is to describe some common connection and filtering

### Homework #11 203-1-1721 Physics 2 for Students of Mechanical Engineering

Homework #11 203-1-1721 Physics 2 for Students of Mechanical Engineering 2. A circular coil has a 10.3 cm radius and consists of 34 closely wound turns of wire. An externally produced magnetic field of

### Chapter 11. Inductors ISU EE. C.Y. Lee

Chapter 11 Inductors Objectives Describe the basic structure and characteristics of an inductor Discuss various types of inductors Analyze series inductors Analyze parallel inductors Analyze inductive

### Diode Applications. by Kenneth A. Kuhn Sept. 1, 2008. This note illustrates some common applications of diodes.

by Kenneth A. Kuhn Sept. 1, 2008 This note illustrates some common applications of diodes. Power supply applications A common application for diodes is converting AC to DC. Although half-wave rectification

### 2. A conductor of length 2m moves at 4m/s at 30 to a uniform magnetic field of 0.1T. Which one of the following gives the e.m.f. generated?

Extra Questions - 2 1. A straight length of wire moves through a uniform magnetic field. The e.m.f. produced across the ends of the wire will be maximum if it moves: a) along the lines of magnetic flux

### TEACHING RESOURCES SCHEMES OF WORK DEVELOPING A SPECIFICATION COMPONENT FACTSHEETS HOW TO SOLDER GUIDE GET IN TUNE WITH THIS FM RADIO KIT. Version 2.

TEACHING RESOURCES SCHEMES OF WORK DEVELOPING A SPECIFICATION COMPONENT FACTSHEETS HOW TO SOLDER GUIDE GET IN TUNE WITH THIS FM RADIO KIT Version 2.0 Index of Sheets TEACHING RESOURCES Index of Sheets

### 1. The diagram below represents magnetic lines of force within a region of space.

1. The diagram below represents magnetic lines of force within a region of space. 4. In which diagram below is the magnetic flux density at point P greatest? (1) (3) (2) (4) The magnetic field is strongest

### 45. The peak value of an alternating current in a 1500-W device is 5.4 A. What is the rms voltage across?

PHYS Practice Problems hapters 8- hapter 8. 45. The peak value of an alternating current in a 5-W device is 5.4 A. What is the rms voltage across? The power and current can be used to find the peak voltage,

### Inductance. Motors. Generators

Inductance Motors Generators Self-inductance Self-inductance occurs when the changing flux through a circuit arises from the circuit itself. As the current increases, the magnetic flux through a loop due

### Building the HVPS High Voltage Power Supply

Introduction Building the HVPS High Voltage Power Supply Voltages higher than the LVPS provides kilovolts are needed in later experiments to get strong electric fields and to generate microwaves. The high-voltage

### AC Generators. Basic Generator

AC Generators Basic Generator A basic generator consists of a magnetic field, an armature, slip rings, brushes and a resistive load. The magnetic field is usually an electromagnet. An armature is any number

### ElectroMagnetic Induction. AP Physics B

ElectroMagnetic Induction AP Physics B What is E/M Induction? Electromagnetic Induction is the process of using magnetic fields to produce voltage, and in a complete circuit, a current. Michael Faraday

### Impedance Matching and Matching Networks. Valentin Todorow, December, 2009

Impedance Matching and Matching Networks Valentin Todorow, December, 2009 RF for Plasma Processing - Definition of RF What is RF? The IEEE Standard Dictionary of Electrical and Electronics Terms defines

### Application Note. So You Need to Measure Some Inductors?

So You Need to Measure Some nductors? Take a look at the 1910 nductance Analyzer. Although specifically designed for production testing of inductors and coils, in addition to measuring inductance (L),

### Single Transistor FM Transmitter Design

Single Transistor FM Transmitter Design In telecommunications, frequency modulation (FM) conveys information over a carrier wave by varying its frequency. FM is commonly used at VHF radio frequencies for

### EDEXCEL NATIONAL CERTIFICATE/DIPLOMA UNIT 5 - ELECTRICAL AND ELECTRONIC PRINCIPLES NQF LEVEL 3 OUTCOME 4 - ALTERNATING CURRENT

EDEXCEL NATIONAL CERTIFICATE/DIPLOMA UNIT 5 - ELECTRICAL AND ELECTRONIC PRINCIPLES NQF LEVEL 3 OUTCOME 4 - ALTERNATING CURRENT 4 Understand single-phase alternating current (ac) theory Single phase AC

### BASIC ELECTRONICS AC CIRCUIT ANALYSIS. December 2011

AM 5-202 BASIC ELECTRONICS AC CIRCUIT ANALYSIS December 2011 DISTRIBUTION RESTRICTION: Approved for Pubic Release. Distribution is unlimited. DEPARTMENT OF THE ARMY MILITARY AUXILIARY RADIO SYSTEM FORT

### Looking at Capacitors

Module 2 AC Theory Looking at What you'll learn in Module 2: In section 2.1 Common capacitor types and their uses. Basic Circuit Symbols for. In section 2.2 Charge & Discharge How capacitors work. What

### The DC Motor/Generator Commutation Mystery. Commutation and Brushes. DC Machine Basics

The DC Motor/Generator Commutation Mystery One small, yet vital piece of the DC electric motor puzzle is the carbon brush. Using the correct carbon brush is a key component for outstanding motor life,

### Lecture - 4 Diode Rectifier Circuits

Basic Electronics (Module 1 Semiconductor Diodes) Dr. Chitralekha Mahanta Department of Electronics and Communication Engineering Indian Institute of Technology, Guwahati Lecture - 4 Diode Rectifier Circuits

### Circuits with inductors and alternating currents. Chapter 20 #45, 46, 47, 49

Circuits with inductors and alternating currents Chapter 20 #45, 46, 47, 49 RL circuits Ch. 20 (last section) Symbol for inductor looks like a spring. An inductor is a circuit element that has a large

### GenTech Practice Questions

GenTech Practice Questions Basic Electronics Test: This test will assess your knowledge of and ability to apply the principles of Basic Electronics. This test is comprised of 90 questions in the following

### Inductor and Magnetic Product Terminology

INTRODUCTION IFC LPT ILB IHSM IM IMC LPE TJ LPC IRF IHB The scope of this application note is to define the terminology associated with inductors and their applications. Some of these terms are listed

### OHM S LAW AND RESISTANCE

OHM S LAW AND RESISTANCE Resistance is one of the basic principles of Ohm s law, and can be found in virtually any device used to conduct electricity. Georg Simon Ohm was a German physicist who conducted

### Using and Wiring Light Emitting Diodes (LEDs) for Model Railroads

Using and Wiring Light Emitting Diodes (LEDs) for Model Railroads LEDs have many useful applications in Model railroading, including: Locomotive headlights Rear-end warning lights for cabooses and passenger

### Voltage, Current, Resistance, Capacitance and Inductance

Voltage, Current, Resistance, Capacitance and Inductance Really basic electrical engineering. 1 Electricity and conductors Electricity is the movement of electrons. Electrons move easily through a conductor

### COMPONENT COLOR BAND CHARTS v.1

COMPONENT COLOR CHARTS v.1 Use the following charts to calculate component values for color band resistors, capacitors and inductors. The charts are for 4, 5 and 6-band resistors; 4-band capacitors and

### 104 Practice Exam 2-3/21/02

104 Practice Exam 2-3/21/02 1. Two electrons are located in a region of space where the magnetic field is zero. Electron A is at rest; and electron B is moving westward with a constant velocity. A non-zero

### Solution Derivations for Capa #11

Solution Derivations for Capa #11 Caution: The symbol E is used interchangeably for energy and EMF. 1) DATA: V b = 5.0 V, = 155 Ω, L = 8.400 10 2 H. In the diagram above, what is the voltage across the

### Critical thin-film processes such as deposition and etching take place in a vacuum

WHITEPAPER INTRODUCING POWER SUPPLIES AND PLASMA Critical thin-film processes such as deposition and etching take place in a vacuum SYSTEMS chamber in the presence of a plasma. A plasma is an electrically

### Digital Energy ITI. Instrument Transformer Basic Technical Information and Application

g Digital Energy ITI Instrument Transformer Basic Technical Information and Application Table of Contents DEFINITIONS AND FUNCTIONS CONSTRUCTION FEATURES MAGNETIC CIRCUITS RATING AND RATIO CURRENT TRANSFORMER

### INTERNATIONAL ATOMIC ENERGY AGENCY INSTRUMENTATION UNIT SMD (SURFACE MOUNTED DEVICES) REPAIR S. WIERZBINSKI FEBRUARY 1999

(SURFACE MOUNTED DEVICES) REPAIR S. WIERZBINSKI FEBRUARY 1999 (SURFACE MOUNTED DEVICES) REPAIR 1 TABLE OF CONTENTS PAGE 1. INTRODUCTION 3 2. ADVANTAGES 4 3. LIMITATIONS 4 4. DIALECT 5 5. SIZES AND DIMENSIONS

### Motor Fundamentals. DC Motor

Motor Fundamentals Before we can examine the function of a drive, we must understand the basic operation of the motor. It is used to convert the electrical energy, supplied by the controller, to mechanical

### THE LUCAS C40 DYNAMO & ITS ARMATURE.

THE LUCAS C40 DYNAMO & ITS ARMATURE. H. Holden, March 2011. The Dynamo as a DC generating machine was used extensively in the pre- Alternator era, from the early 1900 s up to the late 1960 s and early

### Introduction to Electricity & Magnetism. Dr Lisa Jardine-Wright Cavendish Laboratory

Introduction to Electricity & Magnetism Dr Lisa Jardine-Wright Cavendish Laboratory Examples of uses of electricity Christmas lights Cars Electronic devices Human body Electricity? Electricity is the presence

### Capacitors in Circuits

apacitors in ircuits apacitors store energy in the electric field E field created by the stored charge In circuit apacitor may be absorbing energy Thus causes circuit current to be reduced Effectively

### Drive circuit basics + V. τ e. Industrial Circuits Application Note. Winding resistance and inductance

ndustrial Circuits Application Note Drive circuit basics For a given size of a stepper motor, a limited space is available for the windings. n the process of optimizing a stepper motor drive system, an

### Magnetic Field of a Circular Coil Lab 12

HB 11-26-07 Magnetic Field of a Circular Coil Lab 12 1 Magnetic Field of a Circular Coil Lab 12 Equipment- coil apparatus, BK Precision 2120B oscilloscope, Fluke multimeter, Wavetek FG3C function generator,

### DC Circuits (Combination of resistances)

Name: Partner: Partner: Partner: DC Circuits (Combination of resistances) EQUIPMENT NEEDED: Circuits Experiment Board One Dcell Battery Wire leads Multimeter 100, 330, 1k resistors Purpose The purpose

### Mutual Inductance and Transformers F3 3. r L = ω o

utual Inductance and Transformers F3 1 utual Inductance & Transformers If a current, i 1, flows in a coil or circuit then it produces a magnetic field. Some of the magnetic flux may link a second coil

### ECEN 1400, Introduction to Analog and Digital Electronics

ECEN 1400, Introduction to Analog and Digital Electronics Lab 4: Power supply 1 INTRODUCTION This lab will span two lab periods. In this lab, you will create the power supply that transforms the AC wall

Germanium Diode AM Radio LAB 3 3.1 Introduction In this laboratory exercise you will build a germanium diode based AM (Medium Wave) radio. Earliest radios used simple diode detector circuits. The diodes

### Direction of Induced Current

Direction of Induced Current Bar magnet moves through coil Current induced in coil A S N v Reverse pole Induced current changes sign B N S v v Coil moves past fixed bar magnet Current induced in coil as

### Study Guide for the Electronics Technician Pre-Employment Examination

Bay Area Rapid Transit District Study Guide for the Electronics Technician Pre-Employment Examination INTRODUCTION The Bay Area Rapid Transit (BART) District makes extensive use of electronics technology

### VJ 6040 Mobile Digital TV UHF Antenna Evaluation Board

VISHAY VITRAMON Multilayer Chip Capacitors Application Note GENERAL is a multilayer ceramic chip antenna designed for receiving mobile digital TV transmissions in the UHF band. The target application for

### The purposes of this experiment are to test Faraday's Law qualitatively and to test Lenz's Law.

260 17-1 I. THEORY EXPERIMENT 17 QUALITATIVE STUDY OF INDUCED EMF Along the extended central axis of a bar magnet, the magnetic field vector B r, on the side nearer the North pole, points away from this

### STUDY GUIDE: ELECTRICITY AND MAGNETISM

319 S. Naperville Road Wheaton, IL 60187 www.questionsgalore.net Phone: (630) 580-5735 E-Mail: info@questionsgalore.net Fax: (630) 580-5765 STUDY GUIDE: ELECTRICITY AND MAGNETISM An atom is made of three

### Last time : energy storage elements capacitor.

Last time : energy storage elements capacitor. Charge on plates Energy stored in the form of electric field Passive sign convention Vlt Voltage drop across real capacitor can not change abruptly because

### Energy in Electrical Systems. Overview

Energy in Electrical Systems Overview How can Potential Energy be stored in electrical systems? Battery Stored as chemical energy then transformed to electrical energy on usage Water behind a dam Water

### Experiment #5, Series and Parallel Circuits, Kirchhoff s Laws

Physics 182 Summer 2013 Experiment #5 1 Experiment #5, Series and Parallel Circuits, Kirchhoff s Laws 1 Purpose Our purpose is to explore and validate Kirchhoff s laws as a way to better understanding

### Iron Powder Cores for Switchmode Power Supply Inductors. by: Jim Cox

HOME APPLICATION NOTES Iron Powder Cores for Switchmode Power Supply Inductors by: Jim Cox Purpose: The purpose of this application note is to cover the properties of iron powder as a magnetic core material

### UNIT 3 AUTOMOBILE ELECTRICAL SYSTEMS

UNIT 3 AUTOMOBILE ELECTRICAL SYSTEMS Automobile Electrical Structure 3.1 Introduction Objectives 3.2 Ignition System 3.3 Requirement of an Ignition System 3.4 Types of Ignition 3.4.1 Battery or Coil Ignition

### Introduction to the Smith Chart for the MSA Sam Wetterlin 10/12/09 Z +

Introduction to the Smith Chart for the MSA Sam Wetterlin 10/12/09 Quick Review of Reflection Coefficient The Smith chart is a method of graphing reflection coefficients and impedance, and is often useful

### Chapter 30 Inductance

Chapter 30 Inductance - Mutual Inductance - Self-Inductance and Inductors - Magnetic-Field Energy - The R- Circuit - The -C Circuit - The -R-C Series Circuit . Mutual Inductance - A changing current in

### The W5JCK Guide to the Mathematic Equations Required for the Amateur Extra Class Exam

The W5JCK Guide to the Mathematic Equations Required for the Amateur Extra Class Exam This document contains every question from the Extra Class (Element 4) Question Pool* that requires one or more mathematical

### LM 358 Op Amp. If you have small signals and need a more useful reading we could amplify it using the op amp, this is commonly used in sensors.

LM 358 Op Amp S k i l l L e v e l : I n t e r m e d i a t e OVERVIEW The LM 358 is a duel single supply operational amplifier. As it is a single supply it eliminates the need for a duel power supply, thus

### CONSTRUCTING A VARIABLE POWER SUPPLY UNIT

CONSTRUCTING A VARIABLE POWER SUPPLY UNIT Building a power supply is a good way to put into practice many of the ideas we have been studying about electrical power so far. Most often, power supplies are

### The DC Motor. Physics 1051 Laboratory #5 The DC Motor

The DC Motor Physics 1051 Laboratory #5 The DC Motor Contents Part I: Objective Part II: Introduction Magnetic Force Right Hand Rule Force on a Loop Magnetic Dipole Moment Torque Part II: Predictions Force

Division of Spang & Company Technical Bulletin BULLETIN SR-1A INDUCTOR DESIGN IN SWITCHING REGULATORS Better efficiency, reduced size, and lower costs have combined to make the switching regulator a viable

### REPORT ON CANDIDATES WORK IN THE CARIBBEAN ADVANCED PROFICIENCY EXAMINATION MAY/JUNE 2008 ELECTRICAL AND ELECTRONIC TECHNOLOGY (TRINIDAD AND TOBAGO)

CARIBBEAN EXAMINATIONS COUNCIL REPORT ON CANDIDATES WORK IN THE CARIBBEAN ADVANCED PROFICIENCY EXAMINATION MAY/JUNE 2008 ELECTRICAL AND ELECTRONIC TECHNOLOGY (TRINIDAD AND TOBAGO) Copyright 2008 Caribbean

### Chapter 7. Magnetism and Electromagnetism ISU EE. C.Y. Lee

Chapter 7 Magnetism and Electromagnetism Objectives Explain the principles of the magnetic field Explain the principles of electromagnetism Describe the principle of operation for several types of electromagnetic

### EE301 Lesson 14 Reading: 10.1-10.4, 10.11-10.12, 11.1-11.4 and 11.11-11.13

CAPACITORS AND INDUCTORS Learning Objectives EE301 Lesson 14 a. Define capacitance and state its symbol and unit of measurement. b. Predict the capacitance of a parallel plate capacitor. c. Analyze how

### UNDERSTANDING AND CONTROLLING COMMON-MODE EMISSIONS IN HIGH-POWER ELECTRONICS

Page 1 UNDERSTANDING AND CONTROLLING COMMON-MODE EMISSIONS IN HIGH-POWER ELECTRONICS By Henry Ott Consultants Livingston, NJ 07039 (973) 992-1793 www.hottconsultants.com hott@ieee.org Page 2 THE BASIC

### Coupled Inductors. Introducing Coupled Inductors

Coupled Inductors From power distribution across large distances to radio transmissions, coupled inductors are used extensively in electrical applications. Their properties allow for increasing or decreasing

### Wires & Connections Component Circuit Symbol Function of Component. Power Supplies Component Circuit Symbol Function of Component

Lista Dei Simboli Dei Circuiti Per i Componenti Elettronici Wires & Connections Wire Wires joined Wires not joined To pass current very easily from one part of a circuit to another. A 'blob' should be

### BSNL TTA Question Paper-Instruments and Measurement Specialization 2007

BSNL TTA Question Paper-Instruments and Measurement Specialization 2007 (1) Instrument is a device for determining (a) the magnitude of a quantity (b) the physics of a variable (c) either of the above

### SECTION 4 ELECTRIC MOTORS UNIT 17: TYPES OF ELECTRIC MOTORS

SECTION 4 ELECTRIC MOTORS UNIT 17: TYPES OF ELECTRIC MOTORS UNIT OBJECTIVES After studying this unit, the reader should be able to Describe the different types of open single-phase motors used to drive

### Understanding the Alternator

http://www.autoshop101.com THIS AUTOMOTIVE SERIES ON ALTERNATORS HAS BEEN DEVELOPED BY KEVIN R. SULLIVAN PROFESSOR OF AUTOMOTIVE TECHNOLOGY AT SKYLINE COLLEGE SAN BRUNO, CALIFORNIA ALL RIGHTS RESERVED

### Theory of Transistors and Other Semiconductor Devices

Theory of Transistors and Other Semiconductor Devices 1. SEMICONDUCTORS 1.1. Metals and insulators 1.1.1. Conduction in metals Metals are filled with electrons. Many of these, typically one or two per

### PS-6.2 Explain the factors that determine potential and kinetic energy and the transformation of one to the other.

PS-6.1 Explain how the law of conservation of energy applies to the transformation of various forms of energy (including mechanical energy, electrical energy, chemical energy, light energy, sound energy,

### Operating Instructions

D-TEK Vehicle Loop Detector Operating Instructions This product is an accessory or part of a system. Always read and follow the manufacturer s instructions for the equipment you are connecting this product

### Chapter 19 Operational Amplifiers

Chapter 19 Operational Amplifiers The operational amplifier, or op-amp, is a basic building block of modern electronics. Op-amps date back to the early days of vacuum tubes, but they only became common

### Understanding SMD Power Inductors. Application Note. July 2011

Understanding SMD Power Inductors July 2011 Application Note Power inductors play an important role in voltage conversion applications by yielding lower core losses. They are also used to store energy,

### BURGLAR ALARM KIT MODEL K-23. Assembly and Instruction Manual ELENCO

BURGLAR ALARM KIT MODEL K-23 Assembly and Instruction Manual ELENCO Copyright 2013, 1989 ELENCO Electronics, Inc. Revised 2011 REV-Q 753223 No part of this book shall be reproduced by any means; electronic,

### High voltage power supply (1 to 20 KV)

High voltage power supply ( to 0 KV) Ammar Ahmed Khan, Muhammad Wasif, Muhammad Sabieh Anwar This documentation is divided into two parts, the first part provides a brief overview about the key features

### Transformer Calculations

Transformer Calculations Transformers Transformers are one of the most basic yet practical devices used today. No matter where you are there is always a transformer nearby. They are used throughout alternating-current

### Linear DC Motors. 15.1 Magnetic Flux. 15.1.1 Permanent Bar Magnets

Linear DC Motors The purpose of this supplement is to present the basic material needed to understand the operation of simple DC motors. This is intended to be used as the reference material for the linear

### Sinusoidal. Oscillators

364 4 Principles of Electronics Sinusoidal Oscillators 4. Sinusoidal Oscillator 4.2 Types of Sinusoidal Oscillations 4.3 Oscillatory Circuit 4.4 Undamped Oscillations from Tank Circuit 4.5 Positive Feedback

### Building the AMP Amplifier

Building the AMP Amplifier Introduction For about 80 years it has been possible to amplify voltage differences and to increase the associated power, first with vacuum tubes using electrons from a hot filament;